Injector testing off-car

Testing injectors:

To check the injectors and to see if they are in good working condition we measure the resistance in their windings to make sure they are in good condition. The manufacturers specification for the types we were using (without resistor) was 14-17 Ohms. they all seemed to be in good working condition. Earth leakage by checking the resistance between the earth terminal and body of the injector , This should be OL which means the there is no part of the injector(specialy windings) has not been earthed out thru the body injector. If there is a reading between the earth and the body that means the injector is faulty and is shorting out thru the body which means it needs to be replaced.

Now we have wired up the injectors to a power supply and I can hear them ticking as I turn the power on and off. This shows that they are opening and closing in the right manner and internal parts are in working condition.

Other engine problems that could give us the same results as an injector not working could be :

Fuel pump siezed or not working , Fuel filter blocked , Fuel line broken or no petrol in the tank.

Next test is injector spray pattern test to make sure they are spraying an even cone shape without any distortion , this is to make sure the fuel is getting fully atomised and fuel is not just running in the manifold.

Next test is to check the Delivery volume of the injector and to compare this results against the manufaturer spec but a little variation between the injectors is ok. If the flow is restricted within the injector, the delivery volume is reduced therefor that cylinder will run lean.

An other and the last test we did was the injector leakage(dribble) test. We do this by applying full line pressure to the injectors without operating them . Fuel leakes and passes the seats and will drip from the injector nozzle... Most of the manufaturer spec specifies only 1 drop per minute is acceptable and any more that is not and needs to be rectified .